AlN dispersion reinforced aluminum matrix composite

Aluminum powders partially nitrided by nitrogen (patent F n(o) 941383 - 11/18/1994) can be used for aluminum - aluminum nitride composite powders. Milling was carried out under inert atmosphere. The final particle size was less than 150 nm for AlN and 75 nm for Al depending the milling time. AlN has a specific abrasive effect. The powder characterisation was made by SEM, TEM and X-rays diffraction. The uniaxial pressure solid state sintering for powder containing 8 to 25 vol% AlN was carried out under vacuum using an optimised cycle (pressure, temperature). The given materials were free of porosity with a metallic aspect. TEM studies show a homogeneity on a micrometer scale which depends on the AlN content. Mechanical properties (Young modulus, modulus of rupture, microhardness), thermal expansion and thermal diffusion coefficients were measured as a function of composition and homogeneity.